Pliosaur

In tiny Thermopolis, Wyo., paleontologists discovered Jurassic period dinosaur bones. Because of that history, the Wyoming Dinosaur Center was opened on the very spot where the bones were dug up.

The center houses both a dinosaur museum dedicated to explaining the evolution of dinosaurs (not just Wyoming dinosaurs) to the public, and a dig site where the public can see how paleontologists work. Some of the dinosaurs presented inside are actual bones, while others are casts, but all are meant to accurately represent the size and realism of the actual species.

Dimetrodon

A Dimetrodon, as seen in the Wyoming Dinosaur Center. According to the museum, a Dimetrodon "is the best known 'sailed reptile (Pelycosaurus). It was a large predator of the early Permian period of Texas. This ferocious animal is thought to be an important link to the mammal-like reptiles that evolved in the late Permian and early Triassic periods. The characteristic spines on its back were covered with thin skin and formed a 'sail.' This sail acted like a solar panel, absorbing heat from the sunlight or cooling in the breeze of the shade, thus regulating the body temperature."

Bellusaurus chomped

In this image, a Bellusaurus being attacked by one of its predators has only one line of defense: Trying to shake off its attacker by violently swinging its tail.

A Bellusaurus is a sauropod dinosaur that would have lived in the Middle Jurassic period of China, according to the Wyoming Dinosaur Center.

As many as 17 of these dinosaurs were found, and were originally thought to be fairly small. But the discovery of a dinosaur called a Klamelisaurus, an adult, in the same area, may have demonstrated that the 17 were a group of cow-sized juvelines, perhaps buried in a flash flood.

Archaeopteryx

Thermopolis' real dinosaur claim to fame comes from the discovery there of one of the best-preserved Archaeopteryx in the world. An Archaeopteryx is a small winged dinosaur related to birds, though its skeleton more resembles that of a small carnivorous dinosaur. That combination supported Charles Darwin's theory, as presented in 1859 in "On the Origin of Species," that, as a sign in the museum puts it, "if evolution had occurred, paleontologists should find extinct birds that were transitional between modern birds and reptiles."

"Unlike most other specimens, which were preserved on their side," the museum's explanation reads, "the Thermopolis Specimen died on its stomach, squishing it into a 'road-kill' posture as overlaying sediments compacted it. This position has allowed scientists to glimpse portions of the skull and limbs never before seen, but it can also make it harder for the average person to tell what they are looking at."

The sign explains that the creature's foot is precisely the same as that of a carnivorous dinosaur. "The ankle bones do not fuse, like in living birds, and the large roller-joint on the second toe show that Archaeopteryx had a hyper-extendable 'killer claw' like its cousin, Velociraptor.

"The skull is preserved in a three-fourths view, making the teeth harder to see, but letting scientists glimpse the bones of the palate. The four-pronged bone that supports the palate is like dinosaurs, and unlike the three-pronged palatine of modern birds.

"While Archaeopteryx has feathered 'wings,' the hand is fully functional three-clawed dinosaur hand, not the fused, almost immobile hand of modern birds."

Tuojiangosaurus

This spiky-backed dinosaur, the Tuojiangosaurus, was related to the Stegosaurus, and the two species were contemporaries, both living about 150 million years ago. But where the Stegosaurus was a North American dinosaur, the more primitive Tuojiangosaurus was from Asia.

What was the role of this beast's plates and spikes? "Like with Stegosaurus, they may have served many functions," according to the museum. "The plates would have helped keep predators at bay. They may also have helped to attract mates. It has even been suggested that Stegosaur plates may have helped their owners cool down."

Jimbo

According to the Wyoming Dinosaur Center, at 106 feet, Jimbo, the second Supersaurus specimen to ever be found, is the biggest dinosaur discovered in Wyoming, and one of the longest ever to prowl terra firma.

With the lens CNET News reporter Daniel Terdiman used to take this picture, it's hard to judge Jimbo's length, but note that the creature is actually 106 feet long.

"It took a decade of hard work to remove Jimbo's remains from the rocks that entombed him near Douglas, Wyoming. As research has progressed, this specimen has shed new light on how large the biggest dinosaurs were, and how the whip-tailed sauropods were related to one another," the museum noted.

Othnielia Rex

Allosaurus Fragilis

The Allosaurus, a carnivore from Jurassic North America, about 145 million to 150 million years ago.

A sign in the museum reads, "Allosaurus is often thought of as the T.rex of its time. While T.rex massed as much as 6 tons, an average Allosaurus would have weighed in at 'just' 1.5 tons. The is strange because some of the plant-eating dinosaurs that lived during the time of Allosaurus got much bigger than the prey of T.rex. Some paleontologists think that Allosaurus must have hunted smaller types of dinosaurs, or juveniles of the larger ones. Other scientists think that large packs of twenty or more may have hunted even the largest prey animals in its environment."

Mymoorapelta maysi

"Mymoorapelta was an early member of the armored dinosaurs known as ankylosaurs" reads a sign in the museum. "These dinosaurs had very extensive armor, making it difficult for a meat-eater to take a bite of their juicy innards. Mymoorapelta was built low to the ground so its armored back would offer the best protection possible."

Deinonychus

A petite carnivore, reaching just nine feet long and 3.5 feet high, and less than 200 pounds, Deinonychus was a close relative of the Velociraptor, and both species featured long, bird-like arms, but the former had a long snout, big eyes and sharp serrated teeth, and possibly feathers. Its "killing claws," large and curved on its hind feet, were likely Deinonychus' main weapon. "Leaping onto prey and slashing at them like a Mesozoic kick-boxer. These claws give Deinonychus its name, which is derived from the Greek 'deinos,' (which equals) terrible, and 'onux,' (which means) claw."

Velociraptor

Velociraptor is usually presented as a scaly, almost lizard-like dinosaur, the museum explains, but in fact, was probably covered in feathers and more like a "killer chicken."

A museum sign reads, "So how do scientists know that Velociraptor was feathered rather than scaly? A remarkable series of fossils have been found which preserved feather impressions. There are literally dozens of these fossils now, and many different meat-eating dinosaurs are represented. Very close relatives of Velociraptor, such as Microraptor and Jinfengopteryx, has not only fur-like feathers, but true wing and tail feathers. In fact, every single close relative of Velociraptor found with skin impressions, without exception, was found with proto-wings. Scientists are as confident that Velociraptor had wing feathers as they are that extinct cave bears had fur."

Triceratops

This is Triceratops, the largest and last surviving horned dinosaur, according to the museum. "It grew as large as a male African elephant. Despite its size, some scientists think it could have achieved a slow, rhino-like gallop, perhaps as fast 25 miles per hour."

T.rex

"Tyrannosaurus rex was one of the largest meat-eaters to walk the Earth," a museum sign on the famous beast reads. "Scientists still disagree how fast it was, though 25-30 miles per hour does not seem unreasonable. At that speed, it could run quicker than all but the fastest human sprinters. More importantly, it...was built to move faster than Triceratops and other potential prey animals of the Late Cretaceous.

"New evidence from close relatives, Tarbosaurus, from Asia, and Albertosaurus, from Canada, suggest that Tyrranosaurus hunted in packs....Because prey such as Triceratops was so dangerous, (T.rex) probably preferred scavenging carcasses, or hunting the less dangerous duck-billed dinosaurs in its environment. When it did hunt horned dinosaurs like Triceratops, it would have tried to startle them into fleeing, letting (T.rex) land a bit to the unprotected rear.

"A single T. rex bite could have gouged out a wound three feet in length, a foot wide and a foot deep! Such a blow would have killed any animal of the time."

T. rex versus Triceratops

This image depicts the way the T. rex and Triceratops are presented in the museum--which is hard to photograph.

In this scenario, the unfortunate Triceratops has become prey by making a very large mistake. By turning tail and running, it exposed its vulnerable rear to the "five-foot-long skull of Tyrannosaurus rex. Triceratops could not outrun T. rex, but its four-point stance may have made it more nimble," according to the museum.

Albertaceratops

This dinosaur has only been known as Albertaceratops since 2007, and the Wyoming Dinosaur Center has presented this, the animal's original skeleton, the only one on display in the world. The specimen is from northern Montana, close to the border with Canada. It was a western North American dinosaur, living 75 million years ago in the Late Cretaceous.

Maiasaura with babies

Here, "a 'duck-billed' dinosaur called Maiasaura tends to a nest of babies," reads a museum sign. "How do we know whether or not these dinosaurs took care of their young?

"In the early days of dinosaur research, nothing was known about the family lives of ancient dinosaurs. In the 1920s, an expedition to Mongolia was the first to unearth fossilized nests of dinosaurs. Clutches of eggs were laid in hollows in the ground.

"But still, little was known about how these dinosaurs grew up. Then, in the 1970s, more dinosaur nests were found in Montana, in a place that is now called Egg Mountain. Most of the nests were Maiasaura nests. Adults, hatchlings, older juveniles and eggs are all known from the same area.

"This nesting area preserves evidence that helps us understand how the dinosaurs lived. Fossils of hatchling Maiasaura, still living in the nest, show wear on their teeth from grinding plant material. This suggests that their parents were bringing food to their babies. For this, the animal was named Maiasaura, which means 'good mother reptile.'"